In the manufacture of braid reinforced hose it is important that the soft inner liner of the hose is stiffened prior to the braiding step. If the inner liner is not stiffened, several undesirable conditions may result. For example, the braid may sink down and imbed itself into the hose and/or the liner may bulge behind the braiding point. Both of these conditions decrease product quality and increase scrap hose generation.
One method disclosed in the art to achieve this necessary stiffening is hose cooling. Hose cooling can be defined as a method of artificially hardening the inner liner portion of a reinforced hose prior to applying the braiding.
U.S. Pat. No. 598,550, discloses subjecting rubber to low temperatures, preferably below 0.degree. F., until it becomes sufficiently rigid and of greatly-impaired elasticity so that it can be handled without the necessity of employing mandrels, formers, or other mechanical supports. While the rubber is in this rigid condition, it is covered with various forms of fabric and additional layers of rubber or other material which may be desired to be applied for a covering. The rubber is cooled by simply subjecting it to any desired or appropriate treatment by which the inner tube becomes, for a temporary period, sufficiently rigid to undergo subsequent treatment.
U.S. Pat. No. 4,019,939, discloses a process for forming a mandrel from congealable fluid which is introduced in liquid form into the hose which is to be treated in a braid reinforcement operation. The hose or tube is filled with fluid and brought in contact with an environment kept at very low temperatures. The fluid is transformed rapidly into a solid bar, causing the material of the tube itself to become rigid. The fluid remains solidified during operations in which the hose must resist mechanical stresses which otherwise would not be endured by its own elements. The solidified liquid is subsequently brought back to liquid form and removed from the hose. The temperature to which the hose must be cooled is a function of the congealable fluid used.
Ford, U.S. Pat. No. 3,953,270, discloses a method of manufacturing flexible high-pressure, textile reinforced, elastomeric hose. The process comprises extruding the inner elastomeric layer on to a flexible mandrel co-extensively therewith and subsequently passing the inner layer progressively through a freeze chamber operative to freeze the layer. When the layer emerges from the freeze chamber it is frozen solid and is immediately passed through a braider which applies a braided textile layer. The freeze chamber is a tubular heat exchanger which is maintained at a temperature of about -60.degree. F. The freezing temperatures are preferably maintained by liquid nitrogen surrounding the freezer tube.
Harper, et al., U.S. Pat. No. 3,871,185 discloses a method and apparatus for flash freezing various articles. The articles to be frozen are transported into, through and out of an elongated freezing chamber. Liquid nitrogen is sprayed onto the articles at one region of the Chamber. Pumping means are provided together with a suction inlet and discharge outlet in the chamber to recirculate the gas at a high velocity. A liquid nitrogen recirculation system is also provided to recirculate the liquid which did not flash to a gas back to the spray headers.
Contal, et al., U.S. Pat. No. 4,414,819, discloses an apparatus for temporarily rendering rigid a product of soft material of elongated form such as rubber tube. The rubber tube is cooled in a tunnel by liquid nitrogen vaporized in an exchanger. A part of the nitrogen travels in counter-flow and another predetermined part travels in equidirectional flow of the tube towards a process station.